Rigid PVCs contain little or no plasticizer and are commonly used in a wide variety of internal uses sheltered from direct outside environmental exposure. Rigid PVCs are known to degrade upon exposure to sunlight, heat and UV, which degrades the polymeric structure of PVCs and generates trapped HCl acid.
Stabilizers are known to reduce the adverse weathering effects of exposure to heat and sun and frequently are added to PVCs used externally.
Calcium carbonates are commonly used as filler materials in PVCs, but are not known to provide weather resistance or resistance to polymeric degradation upon exposure to heat and sunlight.
Caribbean calcium carbonates described as micritic chalk-like, marine based and sedimentary in origin are disclosed in U.S. Pat. No. 5,102,465 for use as filler material in polyester molding compounds.